Sir Martin Sorrell's status as one of Britain's best-paid businessmen will be cemented on Wednesday when the company he founded discloses that he earned close to £30m last year.

Sky News can reveal that Sir Martin, chief executive of WPP Group, the world's biggest marketing services supplier, saw his total remuneration reach a record high in 2013.

His package was boosted by a £22.7m payout disclosed last month from a scheme linked to total shareholder returns during a five-year period in which WPP was the seventh-best performer in the FTSE-100.

Sir Martin’s pay will be outlined in WPP’s annual report, days after the company reported a strong set of results for the first quarter of 2014, with like-for-like revenues growing by 7%.

The document is expected to show that Sir Martin’s overall pay for 2013 was in the region of £29m, 90% of which was performance-related, insiders said on Tuesday.

The £22.7m share payout was made under a scheme called LEAP, which was discontinued last year after feedback from institutional shareholders.

The remainder of Sir Martin’s 2013 package is understood to consist of roughly £4m awarded under a short-term incentive plan, half of which is in shares deferred for two years.

He also received £1.15m in base salary last year, a lower figure than the previous year’s £1.3m, and a reduced pension contribution.

WPP’s status as the world’s biggest supplier of marketing services, through advertising and media buying networks such as J Walter Thompson and MEC, has been under threat from the proposed merger of Omnicom of the US and France’s Publicis.

However, that transatlantic alliance now looks to be in jeopardy, with tax authorities in the UK and the Netherlands resisting overtures to host a new holding company for the combined group.

Disagreements about the management line-up at the new Franco-US company are also said to be undermining the proposed merger.

Sir Martin said last week that the uncertainties about his rivals’ deal was fuelling a surge in new business success at WPP, with recent major client wins including Marks & Spencer and Vodafone.

The WPP boss has been a staunch defender of his pay, frequently pointing to the risks he took to fund its growth during several precarious phases of the company’s existence.

One ally of Sir Martin’s pointed out that during the five-year period covered by the £22.7m share payout, there was a £12.35bn uplift in returns to all WPP’s shareholders.

Reforms to WPP pay policies saw investor support for the company’s remuneration report rebound to 80% last year from a meagre 40% in 2012.

Vince Cable, the Business Secretary, has forced an overhaul of the way companies report executive pay, and handed shareholders a binding vote on future compensation policies.

Votes on the previous year’s pay deals, which saw bloody noses given to boards at Barclays and Pearson last week, remain non-binding.

A WPP spokesman said: "The vast majority of Sir Martin Sorrell's pay relates to the five-year LEAP scheme already disclosed and designed to link long-term shareholder value creation with executive rewards as prescribed in Vince Cable's recent communication with companies."